Hello again friends
So in keeping with my goal to restoring the 2000 L4 ranger I've been puzzled by this lean condition that I occasionally get a code for. I've checked the plumbing for leaks and tightened what I could reach of loose stuff. Today I sprayed around the intake and various fittings but nothing too serious save the IAC where it mates with the throttle body. I removed it and reinstalled it making sure it wasn't ****ed. The paper gasket is too thin and with a vigorous spraying the RPM will definitely change but I do not think it's the biggest fish in this ocean of mystery. I unplugged the egr vaccum hose and surprisingly nothing happened, zero change. I traced that line back to what maybe a solenoid and unplug that solenoid still nothing however out of the two vaccum lines that connect to that solenoid one has a healthy vaccum, the one connected to the booster. The egr sensor or dpfe I think it's called definitely draws vaccum I unplugged the two hoses to be sure. However the egr has no play. So I think it's stuck closed. Could that be my issue? LTFT is at 25% at idle. It's not rough idling and doesn't sputter. However when I rev it high and let off it shakes and seems​ to wanna die upon coming back down. All help is welcome especially if you've experienced similar issues. Thanks all

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2000 Ranger 2.5L 5 speed.
The world is such a better place when we respectfully communicate.

I suggest you record the code and let us know what it is. A lot easier than trying to read your mind, or over your shoulder when you probe the system.
Most engines will suffer a little indigestion when you rap them up, and then close the throttle 'almost' abruptly. Piston and crankshaft inertia can create a pretty good vacuum in the intake when the throttle is closed at 'high' rpm. That can pull oil past the valve stem seals more than normal, and futz up the mix. The oil will add some 'fuel' the computer doesn't know about, diddling with the mix a bit. Personally, I don't think that is a major problem worth of more investigation until it affects economy or driveability.
The EGR is not enable when the engine is at idle. The solenoid valves add and remove vacuum from behind the EGR diaphragm. One design had a 'add' valve to add vacuum to the diaphragm, and a second valve to 'hold' the vacuum at a preset, setting the EGR flow at a specific position, reported by the sensor built in varying resistance as the valve opened and closed. Once set, it would just sit there open to X.Y, for miles. Not at idle, though.
If the IAC gasket leaks, or the IAC itself, either coat the gasket with 'permatex' or other sealer, and re-install, or get a new gasket. The system may also report 'lean' when it encounters misfire, leaving extra O's in the exhaust, which is all it uses to sense. Extra O's mean there wasn't enough HC to consume them in combustion.
tom

I suggest you record the code and let us know what it is. A lot easier than trying to read your mind, or over your shoulder when you probe the system.
Most engines will suffer a little indigestion when you rap them up, and then close the throttle 'almost' abruptly. Piston and crankshaft inertia can create a pretty good vacuum in the intake when the throttle is closed at 'high' rpm. That can pull oil past the valve stem seals more than normal, and futz up the mix. The oil will add some 'fuel' the computer doesn't know about, diddling with the mix a bit. Personally, I don't think that is a major problem worth of more investigation until it affects economy or driveability.
The EGR is not enable when the engine is at idle. The solenoid valves add and remove vacuum from behind the EGR diaphragm. One design had a 'add' valve to add vacuum to the diaphragm, and a second valve to 'hold' the vacuum at a preset, setting the EGR flow at a specific position, reported by the sensor built in varying resistance as the valve opened and closed. Once set, it would just sit there open to X.Y, for miles. Not at idle, though.
If the IAC gasket leaks, or the IAC itself, either coat the gasket with 'permatex' or other sealer, and re-install, or get a new gasket. The system may also report 'lean' when it encounters misfire, leaving extra O's in the exhaust, which is all it uses to sense. Extra O's mean there wasn't enough HC to consume them in combustion.
tom

You're right Tom, the egr is not commanded at idle. I watched a scanner danner video on this particular diagnosis. I removed the cap from the solenoid and while idling I put my finger on the bleed and the engine almost stalled which confirms that the egr is fine and passages aren't blocked.
I'm getting a P0171 code. The LTFT is at 25% at idle and becomes normal at higher RPMs which eliminates fuel pressure as a possible culprit according to scanner danner again. The leak from the IAC is not serious enough to cause this condition. The gasket is new and it's sitting flushed I made sure. #1 from the coil pack feeding the left side has some issues with spark "leaks" but since there are two per cylinder I'm not sure that could cause any major issue. So I'm going to diagnose the dpfe and replace those two hoses. I would hate to throw parts at this but it looks like that's where I'm headed. I'll attempt to replace intake gaskets but if I go that deep I might as well do spark plugs, wires possibly coil, clean injectors and test regulator.

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Oh I forgot, the truck has in some very rare occasions driven so powerfully and effortlessly it left me puzzled. 99.99% of the time it peaks very early with each gear and has a buzzing vibration if I attempt to push it further. I feel it thru the shifter... What could cause that intermittent state where the engine runs so powerfully it feels like a different vehicle but only every blue moon. I just bought it about 3 weeks ago so I'm not sure about the history. I remember when I first unplugged the maf sensor it drove that good. I tried to recreate the same effect unsuccessfully so far

__________________
2000 Ranger 2.5L 5 speed.
The world is such a better place when we respectfully communicate.

In stock wiring form NOT dual ignition. Pretty sure second system is for unburned fuel during exhaust upstroke. (Emission purposes). I understand simple wire change order on coils makes it true dual ignition but I haven't tried. This may help narrow in on your situation by swapping wires plugs and coils.
Ignition issues would be my start since it's easy and may explain the intermittent power restoration. What happens to your STFT when using propane around suspected vacuum leaks? Still check fuel pressure and rule it out personally rather than by theory. Also have you cleaned the MAF?
Lastly, do you get a response (loss of engine rpm) when drawing a vacuum on EGR valve at idle?

In stock wiring form NOT dual ignition. Pretty sure second system is for unburned fuel during exhaust upstroke. (Emission purposes). I understand simple wire change order on coils makes it true dual ignition but I haven't tried. This may help narrow in on your situation by swapping wires plugs and coils.
Ignition issues would be my start since it's easy and may explain the intermittent power restoration. What happens to your STFT when using propane around suspected vacuum leaks? Still check fuel pressure and rule it out personally rather than by theory. Also have you cleaned the MAF?
Lastly, do you get a response (loss of engine rpm) when drawing a vacuum on EGR valve at idle?

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I do get a response​ when egr is activated at idle: car almost stalled. I've been thinking of replacing the fuel filter and eventually cleaning the injectors as part of my vcg job.i cleaned the maf and the readings seem to fluctuate normally based on throttle activity. I'll definitely change the plugs and wires when I do the vcg job just as part of regular maintenance since I got it with 183k.

__________________
2000 Ranger 2.5L 5 speed.
The world is such a better place when we respectfully communicate.

I got a dpfe at the yard and reset the ECM by removing the battery connector for half an hour. The fuel trims are as follows:
LTFT 0% slowly climbing near 7% after a whole day of driving
STFT 25+% right from the start and fluctuating between 14-21% towards the end of day.

__________________
2000 Ranger 2.5L 5 speed.
The world is such a better place when we respectfully communicate.

So far no codes though the LTFT hovers around 20%. I used seafoam in the tank and it really got the truck going so I'll be replacing the fuel filter soon. Maybe even the injectors seeing that they retail for about $75 for the set on ebay with lifetime warranty.

__________________
2000 Ranger 2.5L 5 speed.
The world is such a better place when we respectfully communicate.

Did you 'get it' that the spark plugs on the left(passenger) side do 99.999% of the sparking? The right side plugs are activated 'on command' by the computer whenever there is an 'emissions situation' where they will help cut emissions.
If the left side fails, you will not be able to start the engine. You may be able to swap parts from side to side as a check tool. If the left side is misfiring, you will have excess O2's in the exhaust - they didn't get used in combustion, and still hang around in the exhaust. The O2 sensor doesn't know... just that they are there. Misfire can lead to a false lean condition. Fix the misfire before looking further... IMO.
tom

As I said earlier I'm going to replace all plugs wires and coils. The misfire that I think I sense happens at idle and is rather faint. I do lack power and that's why I'm looking at the fuel delivery system as a possible culprit. Again after the seafoam treatment the engine response was awesome.

__________________
2000 Ranger 2.5L 5 speed.
The world is such a better place when we respectfully communicate.

I know this is a bit old but this sounds like my problem to a t..i have 98 ranger xlt 3.0 2x4 5 speed I have a misfire in 1 and 6 and both banks run lean.. my BAFX scanner said my FT were as follows.
this test engine was warm idling at 1k
LTFT1 25.0 LTFT2 25.0
FT B1S1 10.2 FT B2S1 3.9
FT B1S2 -100.0 ST B2S2 -100.0
STFT1 10.2 STFT2 7.8

this test warmed up at 2.5k rpms for about a min in half
LTFT1 3.1 LTFT2 3.1
FT B1S1 35.2 FT B2S1 25.8
FT B1S2 -100.0 FT B2S2 -100.0
STFT1 34.4 STFT2 8.6
after letting off it went back close to the same.. so why is my sensor 2 running like that.
also as he stated when I rev up even just to 2-3k rpm and let off it almost dies like to the point my gages start bouncing around..... I have changed the plugs wires coil pack with no change to the misfire.. I can unhook 1 and 6 and there's no diff in the idling it will still idle rough.... I'm lost at this point and yes i understand u can get faulty plugs but how many in a row are u going to get iv went thru 3 plugs when just the #1 was misfiring but I still had power and could go when I wanted to.. a wail back my #6 started misfiring hints why I changed plugs wires and coil pack but that was waste as it didn't fix nothing.. so I'm i am stuck with both banks running lean and my 1 and 6 misfiring.. from i have been told misfires can cause banks to run lean which I believe since bank 2 didn't start acting up till #6 started its shit in.....so what can I do to try and figure this misfire crap out because I'm almost to the point of saying the hell with it and driving her till she quits.. iv been trying to figure this out for damn near 6 months now i never get any where.. i have no power or torque i cant even use 5th gear even if I'm running 75 in 4th and go to 5th i can watch my speed and rpm drop and hill well that's like 3rd gear ordeal even if i hit it doing 55mph in 4th ill slow to about 40 45mph and have to put it in 3rd... once i get above about 2.5k rpm it runs smoother and will go.. i have to drive normally at 2.3kish rpm and shift around 4krpm or the nxt gear will be to low even though i would only be around 1.7rpm it'll bog down and ill have to downshift again..... idk its been a pain in my ass here is some videos if u can watch them be sure to find vid#1 and start there

xler8er... Start a new thread. Yours is v6 and the one in the thread is a 4-banger.

Have you done a compression test? I understand the later vulcans can have valve seat recession, causing misfire.
Misfire will also cause a 'lean' condition as the exhaust gas contains a pile of O2 that has not been chemically attached to hydrocarbons... as in DIDN'T burn, leaving excess O2 which is sensed and reported as 'lean'.
tom

xler8er... Start a new thread. Yours is v6 and the one in the thread is a 4-banger.

Have you done a compression test? I understand the later vulcans can have valve seat recession, causing misfire.
Misfire will also cause a 'lean' condition as the exhaust gas contains a pile of O2 that has not been chemically attached to hydrocarbons... as in DIDN'T burn, leaving excess O2 which is sensed and reported as 'lean'.
tom

Damn it I apologize I shearched on Google and this popped up didn't see it was for 4 banger.. just started reading